Presently in the silver halide light-sensitive color photographic material (hereinafter referred to as "light-sensitive material"), reduction color process is employed and a color image is produced by combination of three kinds of dyes derived from yellow-dye-forming couplers, magenta-dye-forming couplers and cyan-dye-forming couplers.
For the magenta dye-forming coupler, which has popularly used in the conventional silver halide light-sensitive photographic materials, pyrazolone-, pyrazolotriazole, pyrazolino benzimidazole- or indanone-type couplers are known and, among these, various types of 5-pyrazolone derivatives are widely used.
For the substituent on the 3-position of the 5-pyrazolone ring in the above-mentioned 5-pyrazolone derivatives, for example, alkyl groups, aryl groups, alkoxy groups described in U.S. Pat. No. 2,439,098, acylamino groups described in U.S. Pat. Nos. 2,369,489 and 2,600,788, and ureide groups described in U.S. Pat. No. 3,558,319 are used. However, these couplers have such defects that they have relatively low coupling activity with the oxidation product of the developing agent and, accordingly, magenta dye images with high density may hardly be obtainable; that density fluctuation of the developed dye image depending on the kind of developer or pH of the developing solution is large; that secondary absorption in the blue color spectrum range is large and that absorption cut in the longer wavelength side of the main absorption is dull; etc.
Further, 3-anilino-5-pyrazplone-type couplers described in U.S. Pat. Nos. 2,311,081, 3,677,764 and 3,684,514, and British Patent Nos. 956,261 and 1,173,513, etc. have advantages that they have relatively high coupling activity and developed color density is high; and that the secondary absorption in the blue color spectrum range is small. However, the main absorption of the dyes obtainable from these conventionally known 3-anilino-5-pyrazolone-type couplers reside relatively in the shorter wavelength side and, therefore, color reproduction performance tends to be degraded. However, coloring performance of this type of coupler is not sufficient yet. Thus, there is a disadvantage that coloring reaction still takes place even after the light-sensitive material is conveyed to a bleaching bath from the developing bath and, as a result, coloring takes place even in the non-image portion, which is so-called "bleach-fogging".
In order to reduce bleach fogging, use of a certain additive has been proposed. For example, a technology of reducing the bleach fogging by the use of aniline derivatives has been disclosed in Japanese Patent O.P.I. Publication No. 58-105147/1983. However, according to our investigation, it is necessary for the above-mentioned additive to be incorporated approximately at an equivalent molar amount to that of the coupler and, therefore, there is a problem that film thickness necessarily be increased to that extent. Moreover, it was found that, by the use of the above-mentioned additive, not only coloring performance per amount of oil is lowered, but coloring performance per added amount of coupler is also lowered in view of improvement of sharpness and reduction in costs.
As couplers having in their molecules a photographically useful group, which is hereinafter referred to as PUG as well, a development inhibitor releasing coupler (DIR coupler), a development scavenger releasing coupler (DSR coupler), a bleach accelerator releasing coupler (BAR coupler), etc. are well known in the art. Respective of these couplers has a PUG on the group which is released upon reaction with the oxidation product of a developing agent, which is hereinafter referred to as an "active point substituent". In the case of the DIR coupler, for example, an oxidation product of the developing agent is reacted with a coupler, while a development inhibitor residing on the active point substituent group came into play on the neighboring silver halide, restricting development, to obtain required photographic property. In the case of these couplers, it is necessary for the PUG to reside on the active point substituent group and in this respect, they are different from couplers having PUG on the point other than active substituting point.
Japanese Patent O.P.I. Publication No. 63-23855/1988 discloses a coupler having a 2-alkoxyphenylthio group on 4-position of pyrazolone and having partially a similar molecular structure as that of the present invention. However, sensitivity and coloring performance of those couplers are still insufficient. Moreover, in spite of the description in the specification, there is defect that lowering in coloring performance when the coupler is processed with a color developing solution containing an alkaline earth metal compound has not sufficiently been overcome, and improvement in this respect has been awaited. There is neither any clear references to couplers having a photographically useful group according to the present invention nor any description implying this. In other words, there is no reference as to superiority of having such the photographically effective group on the position other than the active point. In fact, in the specification of this reference, couplers in which such photographically useful group is on the active point and on the point other than the active point are both dealt on the same rank. In the specification of this reference, among compounds which are neither included in the preferable examples8 nor described in the working examples, compounds having partially common structure of the compounds according to the present invention are occasionally found, however, they had a problem either in sensitivity or coloring performance and, therefore, they were not preferable compounds.